1. Field of the Invention
The present invention relates to a switch tamping machine comprising a machine frame extending in a direction of elongation and supported on undercarriages for mobility on a track resting on ballast, a track lifting and lining unit, lifting and lining drives linking the track lifting and lining unit to the machine frame between the undercarriages, and at least one ballast tamping unit mounted on the machine frame for displacement transversely to the direction of elongation. The tamping unit comprises a carrier frame, a tamping tool carrier vertically adjustably mounted on the carrier frame for vertical displacement along vertical guide means, and a pair of vibratory tamping tools mounted on the tamping tool carrier for reciprocation in the direction of elongation. The switch tamping machine further comprises an auxiliary lifting device for lifting a switch rail transversely spaced from the machine frame, the auxiliary lifting device comprising a vertically adjustable rail engaging tool.
2. Description of the Prior Art
U.S. Pat. No. 5,031,542 discloses such a mobile ballast tamping machine designed especially for operation in switches and rail crossings. Switch work is difficult not only because of the complicated rail configuration in the switch area but particularly because of the heavy weight of track switches due to the fact that the main track is connected to the branch track in this area by long ties. This heavy weight tends to result in inaccuracies during the lifting and lining of the track switch, particularly in view of the fact that the weight is asymmetrically distributed.
The machine disclosed in this patent comprises an elongated machine frame supported on two undercarriages wherebetween lifting and lining drives link a track lifting and lining unit to the machine frame. Four independently transversely adjustable tamping units are mounted on the machine frame rearwardly of the lifting and lining unit in transverse alignment, each tamping unit carrying a pair of vibratory tamping tools reciprocable in the direction of elongation of the machine frame for respectively operating on the gage and field sides of each track rail. Each tamping unit comprises a carrier frame and a tamping tool carrier vertically adjustably mounted thereon. The transverse adjustment of the tamping units enables selected units to be used for tamping the rails of a branch line in the switch area. Either all four or only the two outer tamping units are mounted on the free ends of elongated carrier beams whose opposite ends are pivoted to the machine frame for pivoting about a vertical axis for transverse adjustment of the tamping units. Furthermore, an auxiliary rail lifting device is mounted on the machine frame adjacent the track lifting and lining unit for lifting a branch track rail in a switch laterally adjacent the machine frame. This auxiliary lifting device comprises a frame running on the branch track rail and carrying rail gripping tools, and a pull rod links the auxiliary lifting device frame to the machine frame. Furthermore, a rope connects the auxiliary lifting device frame to a telescopingly extensible carrier arm on top of the machine frame, and a vertical lifting drive connected to the rope enables the auxiliary lifting device to lift the branch track rail. The carrier arm may be horizontally turned 180.degree. so that the auxiliary lifting device may be operated at either side of the machine frame.
The mobile track switch working machine disclosed in U.S. Pat. No. 4,893,565 also has vertically adjustable tamping units and a track lifting and lining unit having flanged wheels running on the track rails and rail gripping lifting hooks and rollers for engaging the rails. An auxiliary rail lifting device is connected to the track lifting and lining unit at each side of the machine frame and comprises a telescopingly extensible carrier arm extending transversely to the machine frame. A rail lifting hook is mounted at the free end of each carrier arm for selective engagement with the rail head or foot of a branch track rail in a track switch, and a vertically adjustable support jack is associated with the rail lifting hook to support the free carrier frame end on the ballast in a crib and to provide an additional lifting force.